For railroad cars adapted to carry vehicles such as automobiles, it is essential that the cargo be enclosed to protect it from theft of components. Such railroad cars are provided with side walls, a roof spanning the side walls and ends that are closed off by doors or door assemblies. Typically, the railroad cars are designed to have a floor and either one or two intermediate decks supported above the floor for holding the vehicles loaded thereon. The vehicles are driven over ramps detechably mounted to an end of the railroad car onto either the floor or deck for loading.
The height of the railroad car is a critical matter. Due to limitations (underpasses, tunnels and the like) along the railway, the overall height of the railroad car is restricted. Especially in the case of cars designed for three levels, i.e., having two decks supported above the floor, the total height of vehicle carried is limited by the height of the railroad car roof above the floor and by the distance between decks. A savings of two or three inches can be of great significance.
A number of end closure (door) designs are known for railroad cars of the type being discussed. Usually, the door assemblies attach to fingers and slide from a closed position to an open position along the inside of the side walls on a suitable guide track or rail that is provided adjacent the bottom edges of the door assemblies. The guide rail does not hinder the operation of the door assemblies; rather; it provides security to the railroad car contents. Where the fingers straddle the guide rail, access may not be gained to the railroad car interior by pulling the bottom edges of a door assembly out and away from an end opening.
Typically, the guide rail of a prior art railroad car extends upwardly from the floor at an end of the car. This extension of guide rail undesirably wastes from two or three inches of effective distance between the floor and intermediate deck of the railroad car. Actually, where it is necessary to bridge the guide rail with a platform, ramp or the like, the floor-to-deck distance is even further diminished.
It is an advantage according to this invention to provide a railroad car adapted to carry vehicles having an end closure with a door bottom guide rail system that does not diminish the effective distance between floor and intermediate deck of the railroad car while maintaining the security of its contents. A similar result has been achieved in several commonly owned, pending U.S. applications. In Ser. No. 783,943, filed Oct. 3, 1985, now U.S. Pat. No. 4,688,490, a continuous, uninterrupted door guide rail for a railroad car is provided with two spring-biased rail sections. These rail sections depress into recesses in the railroad car floor when vehicle tires pass over them during loading and unloading. In Ser. No. 819,408, filed Jan. 14, 1986, now U.S. Pat. No. 4,646,652, a door bottom guide system is provided with a rail having two interrupted portions through which the tires of a vehicle pass during loading and unloading. The door assemblies of said application, when in their closed position, are secured at the interrupted portions by pin mechanisms and correspondingly sized apertures in the railroad car floor.